watson



J. P. WATSON Jan. 31, 1956 GYROSCOPE Filed March 22, 1954 4 Sheets-Sheet 1 INVENTOR. JIMEs R Mason, EMA/e1- IVarre/ f A erz/g Um Y ATTOQA/EYS.

J. P. WATSON GYROSCOPE 4 Sheets-Sheet 3 Filed March 22, 1954 a m 9 a J N w a m W m Wm M m g 1N. /e 4 VWWWM4C E a 22 M A a W M 2 U a, a no. a v 5x5 Q g M K v .w f r 5 9 M 5 a 4, L hvm 17 4 ,w flfl a m r a United States Patent vGYROSCOPE 'lames l'pwatson, Lynwood, Calif.

.Application March 22, 1954, Serial No. 417,598

Claims. (Cl. 7.4-5.1)

This invention relates to improved features ina-gyroscope and, particularly to anirnprovedmethod and means for caging a gyroscope.

Air, land, and sea vehicles and other apparatus of all types make extensive use of gyroscopes for control purposes. The gyroscope forms a stable space reference against which the attitude of its vehicle maybe compared atall times. Under certain circumstances it'is'desirable to-bring theinner gimbal and the outer gimbal of the gyroscope into a predetermined attitude'orv relation with respect to the housing or frame of the gyroscope. Such an operation is known as caging, and when the-inner gimbaland outer gimbal have beenfixed in sucha predetermined attitude with respect :to the framethe'gyroscope issaid to be caged.

It is an object of this inventiontozprovidean improved method and means for caging a gyroscope.

Itis another object of this invention to provide a rapidly operating method and means for caginga gyroscope.

It is a further object of this invention to provide a method and means for caginga gyroscope which requires only a small amount of energy for the cagingoperation, and which subjects the gimbals and gimbal bearings-of the gyroscope to only Ialowstress.

In many gyroscope uses the outer'gimbal is i free to rotate through 360", although the'innerqgimbal is generally restrained by'stop members to anoperatingrange of perhaps 170. The inner gimbal'isgeneral'ly thus restrained because, if'the rotor shaft is allowedto become coaxial with the outer gimbal axis, there is danger of the outer-gimbal spinning'freely in response-to the reaction torque from the rotor orgyroscopicwheel. .However, though many g-yroscopes thus perrnit .a'wide. range of angularoperations of both theouter and=inner. gimbals,

many'caging .systemsof the past have been :so limited that they are capable of caging the gyroscope only when the. inner gimbal and outer gimbal are within a relatively narrow .angle to the caged position. I

It is an object of this invention to provide -a caging methocland means whereby a-gyroscope-may be quickly caged from any operating positionof its-inner and outer gimbals.

Having caged the gyroscope, the time arrives-when it must be uncaged, that is, the gimbals must berfreed to turn freely with respect .to theframe and each other in response to any change in attitude of the frame. .If the uncagingis done slowly there is danger that undesired and false torques and precession maybe suffered'by one or'both gimbals, thus starting the gyroscope oifinthe wrong attitude.

It is therefore an object of this invention to provide a caging means for a gyroscope which may be uncaged quickly.

Furthermore, in the uncaging operation it'isessential that there be no unwantedv kick or torque applied to the gyroscope during the uncaging procedure.

It is, accordingly, another object of this invention to 2 provide a method an'drneans for uncaging-a gyroscope which is .free from-any danger of applying undesired torques to thegyroscope parts during the uncaging operation.

-lt isi-acfurther object of=this invention to provide a method-and means for caging a. gyroscope in which-the gimbals are brought into caged position through the shortest travellpath, thereby minimizing caging time.

'It is a further object of this invention to provide in a gyroscope cagingzmechanisrn irnproved means for-sensing thE POSlt lOII ofthe inner gimbal with respect'to the outer gimbal and. for sensing the position of the outer gimbal with respect to the frame.

It is a. further object of this-invention to provide such a sensing means as above which also-serves as a latching means for latching thegimbals'in cagedposition.

Many air vehicles, particularly missiles, are :subjected to very high acceleration forces. These accelerations thusprovidea powerful operating force which is capable of operating or-actuating mechanism within the missile unless theimechanism is specifically'designed toiguard against such undesired or false operation.

-It is-an object of this invention to: provide a gyroscope caging andiuneaging means which-is virtually free from danger of .such false or'faulty operation through high vehicle acceleration.

Direct the most serious imishaps whichmight occur with the-gyroscope mechanismof an airivehicle is to havethe gyroscope:v accidentally cagedduring'fiight of the vehicle. Suchcaging of necessity means that the*vehicle has .lost its reference, which in most cases, 'resultsin complete loss of the vehicle.

It is .an object of this invention to provide a. fai=l-safe cagingapparatus and method which will automatically revert tonncagedposition of the gyroscope in the event of power. failure in the caging circuit.

-It --is a..further object of this invention to provide'a caging and uncaging mechanism the bulk of WhiC'hiS mounted onthe-frame instead of on the-gimbals, thereby minimizing the danger of unwanted movement of the gimbals under-high acceleration forces, .such .as impact forces.

Themounting of the stationary portion of --the spin motor or gyroscope wheel to-the inner gimbal must be extremely precise and free from movement.

.Itisanobjectof this inventionto provide an improved mountingfor a gyroscope wheel shaft to the innergim'bal of the gyroscope.

In control vmechanisms of the type here under consideration it is generally found necessary to provide several .operating members or linkages whereby certain movementorpositioning of one=partrnay be transmitted to another part such as a sensing. switch. Themovement transmitting member must be-mounted for its necessary movement with an absolute minimum of friction-in order to be compatible with-the smalllow power requirements of, precision apparatusof this type.

-It is, aecordingly, an object of this invention to provide means for mounting a reciprocable actuating or operating member which .is virtually freeffrom friction in. its operation.

'In the assembly of a typical controlling gyroscope ma-ny wires are employed leading to andfrom the gyroscope. Generally, each wire is made to fulfill as many functions as it can in order toiminimize the weight and space taken-by the wiring.

quires only one wire, in addition to the two wires which are essential to carry the caging power, for the purpose of providing adequate control and indication of caging and uncaging.

In housing or in casing apparatus of the general type here under consideration, it is usually a relatively simple problem to seal the apparatus within the case when the case is cylindrical in form. Gyroscopes like some other types of equipment, however, generally lend themselves better to housings or cases having fiat sides. Such cases have a tendency to bulge out along their straight or fiat edges and where this tendency to bulge is most pronounced there results a consequent sealing problem.

It is an object of this invention to provide an improved seal for a container of rectangular form which is uniquely adapted to resist this tendency to bulge on the fiat sides.

In accordance with these and with other objects which will become apparent thereinafter, certain preferred forms or embodiments of the present invention will now be described.

The method and means of the present invention involves essentially successive caging of the inner gimbal followed by caging of the outer gimbal. While it is recognized that in a certain sense the inner gimbal cannot be regarded as actually caged until it is anchored in a predetermined relation with respect to the frame, it has been found expedient herein to regard the inner gimbal as being caged when it is brought to a predetermined position with respect to the outer gimbal with respect to which it is pivotally mounted, and to regard the outer gimbal as being caged when it is brought to a predetermined position with respect to the frame in which it is mounted. Thus the gyroscope itself is not caged until both the inner gimbal and the outer gimbal have been successively caged.

In the present invention the caging operation involves essentially a sensing of the position of the inner gimbal with respect to the outer gimbal. Following this sensing the inner gimbal is rotated in the correct direction to bring it to caged position within the outer gimbal. This caged position is generally one in which the spin motor axis is substantially perpendicular to the outer gimbal axis, although this particular relative attitude is not necessarily essential to the practice of the present invention. This initial sensing of the position of the inner gimbal within the outer gimbal is important in order to prevent the inner gimbal from being driven in the wrong direc tion which would bring it up against one of its two limit stops thereby subjecting its parts to unwanted strains and stresses and further thwarting one of the important objects of this invention which is to bring the gimbals to their relative caged positions in the shortest time possible.

Following caging of the inner gimbal with the outer gimbal, the inner gimbal is latched or secured to the outer gimbal in caged position.

Next the position of the outer gimbal within the frame is sensed. Except in cases where the outer gimbal does not have 360 of freedom, this sensing is not essential to the operation of the apparatus, inasmuch as the outer gimbal is free to turn completely through many revolutions; however, it is highly desirable in order that the controlling mechanism may know in which direction to drive the outer gimbal in order to bringit to caged position with respect to the frame in a minimum time. When the outer gimbal has been properly positioned and latched to the frame, caging is complete.

In the present invention the uncaging is performed in a minimum time by so designing the mechanism that all of the parts which effect the uncaging move in a short straight line as will become more fully apparent hereinafter. At the same time in one form of the present invention the dangerous forces of high acceleration which might cause unwanted operation of the parts are '23 of the frame 21.

circumvented by using a drive mechanism which is rotary in its operation and therefore not subject to the high linear acceleration mentioned hereinbefore.

A detailed description of certain forms of the present invention follows.

Referring to the drawings, Figs. 1 through 14 inclusive illustrate a first embodiment of the present invention and Figs. 15 and 16 indicate certain modifications which may be made thereto if desired.

Fig. l is a perspective view with certain parts partially broken away more clearly to illustrate the interior of the gyroscope.

Fig. 2 is a fragmentary section taken on line 22 in Figure 1.

Fig. 3 is a cross sectional plan view looking down on the top of the gyroscope with the outer housing or case cut through.

Fig. 4 is a sectional elevation taken on the broken .ection line 44 in Fig. 3.

Fig. 5 is a fragmentary section taken on line 5-5 in Figure 3.

Fig. 6 is a fragmentary sectional view taken on line 6-6 in Fig. 4.

Fig. 7 is a partial sectional view taken on the angled section line 77 of Fig. 3.

Fig. 8 is a fragmentary sectional view taken generally on the same lines as Fig. 4, but showing certain partsbroken away and in greater detail.

Fig. 9 is a fragmentary cross-section taken on a line 9--9 in Fig. 8.

Fig. 10 is a fragmentary view generally similar to Fig. and taken on line 1010 in Fig. 8.

Fig. 11 is a fragmentary section of the gyroscope spin motor taken on line 1111 in Fig. 4.

Fig. 12 is a fragmentary view taken generally in the same plane as Fig. 8 but with certain parts broken away for added clarity.

Fig. 13 is a fragmentary section taken on line 1313 in Fig. 12.

Fig. 14 is a schematic diagram illustrating the operating circuit of the gyroscope.

Fig. 15 is a view generally similar to Fig. 7 but showing a modified form of the present invention.

Fig. 16 is a modified form of wiring diagram employed with the gyroscope of Fig. 15.

Referring to the drawings, 21 designates a generally cylindrical skeleton-like frame including a top plate 22 and a bottom plate 23. The frame is held together by four bolts 20 (Fig. 1) which clamp the plates 22 and 23 together using the cylindrical frame member 21 as a spacer. The gyroscope is mounted to any suitable support 24 by providing a downwardly extending axial member 26 formed on the bottom plate 23 and passing through a mounting opening in the support 24. A nut 27 serves to clamp the gyroscope to the support 24. By thus mounting the gyroscope at only one position internal stresses in the gyroscope casing and frame are avoided no matter'how tight the nut 27 may be screwed up. The mounting member 26 also constitutes a convenient means for passing electrical connecting wires (not shown) into the gyroscope. For this purpose pin connectors 28 are mounted within the axial connecting member 26.

Mounted within the frame 21 for rotation about a vertical axis is an outer gimbal 29. Rotatably mounted within the outer gimbal 29 for rotation about a generally horizontal axis is an inner gimbal 31. Rotatably mounted within the inner gimbal 31 for rotation about an axis perpendicular to the inner gimbal axis is a gyroscopic wheel or rotor 32.

Affixed to the lower end of the outer gimbal 29 is an annular member 33 and immediately circumjaeent there to is another annular member 34 affixed to the end plate Together the members 33 and 34 constitute a pick-off means, the details of which are not shown andwhi'ch'are well known 'in the "art. "Such a piCkeoff-means'maybe magnetic,electrostatic-or mayiconstitute an actual physical contact -as .by potentiometer. The 'pick-oifmeansserves to generate a'uniquesignal which may be taken out through the pin connectors 28 to indicate the position 'of the outer gimbal 29 with respect=toithe frame 21. 'Insimilarrmanner -a 'suitable pick-off mechanism, 'shownschematically at .36, is employed to detect and pick-.otf the position of the'inner gimbal"31'withrespect to the outer gimbal29.

"The upper mounting shaft 37 of the outer gimbal 29 supports a plurality. ofslip rings'38 which are contacted by brushes 39, by' means of which powerandsignals may betransmitted to and from the inner portionsof the gyroscope. Asecond set ofirings and brushes (not shown) completes'these circuitsfrom theouter to the inner gimbal'tosupplypick-oif andLthedrive motor of the gyroscopic Wheel '32. Such. means are well known in the'art and will notbedescribed further in this specification.

In-accordance with the presentinvention, means'are provided for sensing the position of the inner gimbal 31 with respect to the .outer .gimbal 29. Such sensing means includes a disc 41 secured to the inner gimbal '31. Over approximately 90 of its arc the disc 41 is provided with a segment 42 having a given radius, and ;over an adjacent 90 segment 43 the disc has a slightly larger radius. The segment 44 oppositethe segment 42.is.the same radius as'the segment 42 and the segment 46 opposite .the segment :43 is the same radius as the segment 43. Theseilatter two segments 44 and 46 do not constitute operating portions .ofthe disc 41 but are so proportioned simply to provide.ba1ancefor the assembly. At the juncture'between the .segments '42 and 43.is a notch 47. having a tapered bottomportion 48.

.Reciprocably mounted in the outer gimbal 29..in position to register with the disc 41isa latching and sensing member, probe 49. At its lower end the probe 49 is provided with a roller51 engageable with the periphery of thedisc41. The member '49 reciprocates in a cupL-like mounting 'shell52 secured through and within the gimbal 29, as shown in Fig. 8. A compression spring .53 acting between the shell 52 and a shoulder.54.on the probe 49 urges the probe 49 to its upper position away from.the disc '41. Akey-way '56 in the probe 49 mates with a small projection'57 formed on the shell "52 to prevent rotation of the .probe 49 in the gimbal .29 while still permitting reciprocation thereof.

The probe-49 is moved up and down in its sensing operationby means ofa ring-like actuatingmember'SS including a central hub portion 59 and an annular plate 61 journalled to the central portion.59. The plate '61 is circular andhas a peripheral groove 62 therein-in which rides a wheel 63 extending from the upper end .of

the probe or member 49 into the groove 62. Plate f6.1

is -1preven,ted from turningby a key fisprojecting downward from plate22, which however does not impede its axial movement. .In the uncaged condition there is no contact between wheel 63 and plate 61. i

The top plate or member 22 of the frame 21 has a centralportion .64 depending therefrom and around this portion 64is mounted the ring-like hub portion59 which is.rotatable therearound and also axially movable thereon. "The central hub 59 is rotatedby'being provided with a pulley groove 166.in which rides a belt 67, the'belt also encircling a drive pulley '68 secured .to a shaft "69 journalled in .the plate22 and extending .therethroug'h. "The upper endof the shaft 69 extends into a gear box 71, power 'for which .is derived from a small electric drive motor "72. When the motor 72 is energized the central hub portion 59 of the actuating member 58 will be rotated. Rotation of the actuating member 58 serves .to

apply a torque to the outer gimbal 29 whenever. the hub 59'islatched tofthe gimbal29, 'as will now be described.

La itching of the hub 59 to .theg'inibal 29 is effected through-a driving ring 73 located within'an internal-cavity 74formedin'the hub i9-and concentric'with 'thehub 59.

6 The fdrivingrin'g '73 is provided with internal'threads 76 andis keyedto the-hub 59by'the provision. of a key=way 77 -formed in the hub '59 which mates .withia'key '78 formed on'the ring' 73.

Secured to the ring 73 and extending downwardly through an opening inthe bottom plate 79 oftheihub 591is a torque'pin 81;to the lower end'of'the'torque pin'81.is'rotatably mounted a small roller 82. 'The mounting of the roller 82 to the'torque pin 81"isi resilient and slightly movable so that the-roller may move up and down slightly with respect to'the pin 81 but is biasedlto its'downward position. The roller-'82 comes into "rolling engagement with'a torque 'ring'or rail83 having arnot'ch therein at a certain predeterminedpoint in which "the roller 82 may'engagetolatchthe .aCtuating'memberSS to the outer gimbal 29. "When thuslatchedto the gimbal 29, the actuatingmember "58 serves to'apply'a" torque to the gimbal 29.

The actuating member 58 is moved 'downwardly with respect to the frame 21*by the provision o'f aipivote'd thread engaging member=84 havingat itslower'end'a toe 86 which maybe selectively moved outward intoengagement with the thread 76in the 'driving'ring 7-3.

If desired'a plurality of members 84 maybe provided spaced circumferentiallyabout ring 73 in order to prevent cramping. Such members '84 maybe "actuated by a common solenoid'107.

When the hub 59'is rotating and the'toe' 86'is engaged in the threa'd'76, the'rotation of the ring 73 effected through the keying 77-78 'causes the ring 73 to screw downwardly within the hub cavity 74.

This downward 'screwingof the driving ring'73 is transmitted-to the central'hub '59 through an annular compression spring 87 located coaxially in the cavity74. *In thus screwing clown, the ring 73 also operates against the upwar'dibias ofa'spring 88,'the lower end ofwhi'ch rests on an annularledge 89 secured-to the central 'frame memberi64.

Thus as the actuating member '58 is moved'downby the action of the drivingring 73, the probe member=49, and more-particularly the roller-51 thereof, is broughtinto engagement with the periphery of the inner gimbaldisc 41. The annular plate 61 is preferably journalledior free rotation with respect to'the central hub 'S9 'by means of 'a series 'of'ballbearings 91. This-is done in order to minimize friction between the non-rotating plate "61 and therotating'hub "59 during caging. Bearing 91-'and key 65 may be orriitte'd if desired, uniting parts "61 'an'd' 59. The onlyelfect of this simplification wouldbe to introduce a-slight torque on the outer gimbal through roller 63.

-As.the driving ring 73 screws down pressing thea'ctuating member 58 ahead-of it,'the roller 51 'of 'the probe 49 engages either the segment 42 or the segment 43 'ofthe disc 41. It'ispossible'tha't the disc 41 may be already in caged position so'that the roller '51 enters directly into the notch 47. This'would simply-accelerate the whole procedure as will presently be seen'hereinafter. "Engagement of the roller 51 with the disc 41 brings to a halt the downward motion of the actuating member58,thus the initial axial position of the central hub 59 is determined by the angular position of the inner gimbal 31 in the'outer gimbal 29.

The driving..ringi73 continues to screw'd'own .untillthe roller 82 engages the torque rail or ring '83. .Atfliis moment the threadengaging-toe 86 snaps into an annular groove 92 formed at .theupper end of the thread 76 and of somewhatllargerradius. In .this position-the ring :73 may be rotated in either direction and stillremain held down by the toe 86, for rotation of 'the hub-member.59 then continues in one direction or the'other until the roller "82 snaps into the 'V-notch Thus the outer gimbal -29 is positively latched .to the central :hub 59 and further torque applied 'throughfthe-beltr67 resultslinthe. application of a. torque in-one di're'ction or'the other to' the'outergimbal 29.

As has been pointed out hereinbefore, in the initial downward movement of the actuating member 58, it is first stopped in a position dependent upon the angular attitude of the inner gimbal 31. This attitude is sensed by a mechanism including certain peripheral concentric cam surfaces formed on the outside of the central hub 59. The lower of these cam surfaces is disposed immediately above the pulley groove 66 and is denominated 59a. Immediately above the cam surface 59a is an annular cam surface 59/; of larger radius than 59a. Above the surface 59b is a cam surface 590.

The axial region corresponding to the surface 590 is divided angularly into two portions, the first portion being denominated 59c as shown in Fig. 7 and being of radius equal to that of 59a. This arcuate segment is approxi mately 180, the remaining 180 of this axial region being occupied by a cam section 5900 which is of radius equal to that of section 59b.

The above mentioned cam surfaces actuate a probe 93 which in turn actuates a reversing microswitch 94 mounted to the upper frame plate 22. The switch actuating probe 93 is secured to the upper frame plate 22 for limited longitudinal reciprocation by a U-shaped leaf spring member 95, the details of which are essentially similar to those described hereinafter in connection with Fig. 5 to which reference is made for further understanding. The switch 94 is single pole double throw. When the actuating member 58 is in upper position as shown in Fig. 7 the actuating probe 93 is in engagement with the surface 59a and the switch 94 is in its upper position in Fig. 14. If in the initial downward movement of the actuating member 58 the roller 51 comes into engagement with the higher cam segment 43, the cam surface 59a is still in engagement with the switch operating probe 93. If, however, the roller 51 is in registry with the segment 42 so that it does not engage the disc 41 until it has moved down far enough to touch the segment 42 then the cam surface 59b has been brought into engagement with probe 93 and the switch 94 has been actuated to its lower position in Fig. 14.

The mechanism thus described constitutes a means for sensing and translating angular position of the disc 41 into a desired linear position of the reversing switch 94 to control precession of the inner gimbal 31 either clockwise or counter-clockwise in order thereby to bring the roller 51 into engagement in the notch 47. The circuit for effecting this selective precession of the inner gimbal and the operations thereof will be described hereinafter. The inner gimbal is precessed in the.desired direction by applying a torque in the proper angular direction to the outer gimbal 29. This torque is applied through the torque pin 81, acuating member 59 and belt 67 by the motor 72.

The inner gimbal is thus rotated by precession in the proper direction until the roller 51 drops into the notch 47. When the roller 51 is thus in registry with the notch 47 it does not drop all the way down to the bottom but drops to an intermediate position shown at 51c in Fig. 10. It is prevented from dropping all the way down by the engagement of a small wheel 96, extending outwardly from the top of the probe 49, with a track 97 formed by an inturned flange on a depending cylindrical track support 98 mounted to the upper frame plate 22. The track 97 is concentric with the outer gimbal 29 as shown in Fig. 7 and extends all the way therearound.

Fundamentally the wheel 96 is mounted on an arbor 99 which is essentially fixed with respect to the probe 49 but which in practice is actually mounted for a slight vertical adjustment because of manufacturing tolerances as will be explained more fully hereinafter. In thus coming to rest on the rail 97 the wheel 96 causes the arbor is in the position 510 in Fig. 10. This essentially locksv ber 59 is in such a position that the reversing switch probe 93 is in engagement with either the cam segment 590 or 59cc. ever position will cause the outer gimbal 29 to be rotated to caged position through the minimum distance and hence in the minimum time.

The caging of the outer gimbal with respect to the gyroscope frame 21 is elfected through the provision of a V-notch 104 (Fig. 13) formed at a preedtermined position in the frame track 97. When the outer gimbal 29 has been rotated in the proper direction by the actuating member 58 until the wheel or roller 96 is in registry with the V-notch 104, the wheel 96 snaps down into the notch 104 thus'allowing the entire assembly to which it is mounted to drop down a slight distance. This now permits the roller 51 to drop fully into engagement with the lower V surface 48 of the notch 47 thus firmly latching the inner gimbal to the outer gimbal without play or creep. At the same time the outer gimbal is latched in similar manner to the frame 21 by the engagement of the wheel or roller 96 in the V-notch 104.

It is quite important that both gimbals be latched in their caged position without play or back lash and to this end the latching notches are both made in V shape. However, since the same member namely the probe 49 carries both of the caging rollers 51 and 96, the roller 96 is mounted with the slight up and down freedom described hereinbefore in connection with Fig. 12. To this end a small leaf spring 106 is mounted to the upper end of the probe member 49 and bears downwardly on the arbor 99 to keep the wheel 96 pressed into engage-- ment with the V-notch 104. The spring 106 is quite firm but is not strong enough to overcome the general downward pressure exerted on the assembly generally by the spring 87 backed by the driving ring or nut 73.

The caging operation is instituted by energization of a solenoid 107 mounted atop the upper plate 22 and having a plunger 108 extending therefrom. A compression spring 109 biases the plunger 108 to inward position. The outer end of the plunger 108 is pivoted at 111 to the pivoted thread engaging member 84 which is in turn pivoted to the upper frame plate 22 at 112. Thus when the plunger 10% is moved outward the thread engaging toe 86 is moved into engagement in the thread 76.

The plunger 108 carries a laterally extending arm 113.

which engages a transfer microswitch 114 (Fig. 3). The switch 114 is a single pole double throw switch (Fig. 14) and is so positioned as to be actuated from one position to the other when toe 86 snaps into the upper circular groove 92 in the driving ring 73. The transfer switch 114 serves to transfer control of the motor 72 to the reversing switch 94 as seen by reference to Fig. 14.

As the annular plate 61 of the actuating member starts to' move down an uncaged microswitch 116 (Fig. 5) is caused to be actuated. The switch 116 is a simple single pole, single throw switch which is in closed position when the annular plate 61 is in uppermost position and is in open position at all other times. This open position is produced by a small spring located inside the switch which operates as soon as pressure is removed from the actuating member 117.

Switch 116 is actuated by up and down movement of plate 61 through a vertical, reciprocably mounted actuating pin. 118, the upper end of which engages the member 117, the lower end being engaged by plate 61. The

pin 118 is relieved at each end and the relieved portion Thus the reversing switch 94 is in which-' fits 'into a;holeforn1ed inthe respective ends of a pair o f; l eaf spring members'llfi and 12 1. As shown inFigL-S the pin 118"passes through the upper frame Plate-22 by means-of a bore 12'2 which is sufficiently larger than the P1111810 provide completeclearance'. {Each of the leaf sprin g niembers 119 and"121 is appreciably wider than his thic lg. and each'is appreciably longer-than it'iswide. One end of the;- leaf spring member-121 is mounted to the plate=2 2 of thetrarrie 21 and the other leaf spring member l liis mounted at one end-togthe-cylindrical frame member' 21. 'The respectivelfree ends of the members 119 and 121 ate substantially aligned vertically andreceivetherespeetiveends of the pin 118 as mentioned hereinbefore. The combination is biased away "from switch "116 sufiiciently to resist anticipated acceleration forces'that would tend to u tilize the mass of actuator lltl to operateswitch-11'6. "This also relieves switch 116 of the added work of displacing, actuato'r'118 before it can reset itself to the open position. This arrangement insuresthat switch 116 will open without fail as soon as plate -61 starts to move down. 7

i The pin; 1 1'8 is thus mounted for limited back and, forth (in-this ease up and down) movement without anyrub- Bing friction of, any ,kind and'with the possibility of sticking completely eliminated. Although the path of movement of each endtof thepin 118 is slightly arcuate, the angle coveredby the arcis so slight by virtue of the'fact that the switch-116 is a mioro-switch requiring very small travelior actuation, that'it is in eifect alinear movement which'is virtuallyfriction free. In unstressed position of theleaf spring members 119 and 121 their free ends are spaced apartja distance slightlylessthan the opposite shoulders formed where the pin 118 is relieved at each eh i- Thus hez i 1181s l fi m y i eng g mentbetween'the members 119 and '121.

, The p pos oi he n age s toh i t indi ate to th exte nal ens d ntr l in circ i tha .thegy os p i ful y un a The un a w h. 1.1 has. its c unterp rt in, a ,c ged swi ch r .2 t mo h da op t unp me p a an a tu db ar eoipr oah a u t n pin 2 Th pin .1 ..i mount ofo l mit d lon i udi al,recip ocat on bet e a P i o lea p in 1.26 and .127 n manne imila t .that d sc be ,herein eforet n nn cti n w th pin Ulla exc p hatthe spring v1.27 u ges Pin 124 stronglytowardswitch 123 so asto maintain-the switch in he op ra d pos t (t e .upp p t on 1 n Fig. 1 4-) excep whe p ing- =l 7i f r e an h ld downhv er Thele sp i g 12 extend b yo d-it lin w th vthe pin 12. mm e es a as actu t n member-effect tozbeengagedtby t-heroller or wheel 96 when thetwheel-fifi steps int he -v; h .104 n the track -.97. as showaain Fig;

The caged switch 123 is a single pole, double throw switch which is maintained-in'itslower position in Fig. 14 hehever 11 i eatsp in o e he .12 r -engag si y t e QHQ 'FQQ and wh ch i in it app positiomin g. ;14.at all other times.

The p i e pa1 nno ono the oagedr h 1 is to indicate to t el x e nal ci cuit that the gy osc p i ful y eas d.

The vcircuit involved in the present invention is-shown in Fig. 14 wherein tthe dotted line .134 represents schematieally the confines ;of.;th,e gyroscope itself. Leading to the. gyroscope arefla pair of .power conductors. 13610 which is applied a conventionalpowersupply, .as :for.-.ex-. ample, 110 volts :1). C. "In one ofthe conductors is an external switch 137 selectively operable to effectuate the caging operation of the gyroscope. When the switch is open the gyroscope is uncaged, and if already caged will revert .tozuncaged position, as will be described hereinafter.

It willbe noted :that the solenoid107 is connected directly across the full llozvoltsbutth-at a voltagedropr Pins resi o ;.1; .& is;in e ;po .e. in the circuit-to the mot '72 which is generally 3.,28 voltfDJiC. motor. The resistor 138 drops the yvoltage jdown'to approximately 56 volts. This voltage isfurther split in two by a pair of series-c'onnected impedance means ,in thejforms of resistors '1'39-an'd 141. The motor72 is connected'betweentthe juncture point between these resistors139and'141 and theswitch am; of the ,double,t hrow reversing switch94 when-the transfer s'witch'114 is in thelower position. Thus when the ,switch,94 is in upper position the current will flow from right toleft in the motor 72;With the circuit being completed through the resistor 1141, and when the switch 94 is in the;lower position current will flow from left to right, with the circuit being completed through the resistor 139. Inthis way the direction of motor rotation may be changedby means of a simple singlepole, doublethrow switch at 94.

All of the switches in Fig. 14 are shown inithe attitude which they assume when the gyroscope is uncaged, that is when the circuit is dc-energized, ,asby opening ofthe external switch'1'37. As thegyroscope completesits cag ing operation, thejlast step is for the switch 123 to move from its upper'to'its lowerposition, therebyde-energiz'zing the1rnotor 72 and'leavin g only the solenoid 107 energized to;keep.the-driving ringv or nut 73 depressed throughlcontinned engagement by the threadrengaging. lever 84. The une'aged switch 116 is.open.at all times except whenthe gyroscope is completely uncaged. Itsfunction is to indicate through theindicating conductor 142 that the gyroscopeis fully uncaged.

Such indication is made througha pair of lights'143, which isa' greenlight,-and 144, which is a red light. Voltage dropping resistors 14.6 are connected in series with the lights 143and 144 simply to dissipate the excess voltage, sinc'e t he lights 1'43 and .1144 are generally designed for less than the fnll circuit voltage.

In theuncaged position, shown in Fig.'1-4, current flows through the greenlamp .143,then'ce across the bridging conductor 142 and-switch116 to the other side of the; line through the resistjor .138. Theresistance of 138 is so low compared to theresistances @1'44 and 146 that'for practical purposes itmayhe regarded as. a shunt circuit around the red lamp 1.44 sothat the red lamp does not glow at all. In the caged position of the gyroscope the switch 123 is in its lpwerlpositionand the switch 116 is open. Under this reurnstano i fi thegr enlamp'14 which i h nt while the rjed lamp 144 receives the full line voltage, com- Pen a e .or...of cour y.itsseries esistanc 146; t us th redjamp glowsifully andthe green light is out when the gyr s p "is fu y eas d- Duringtlie cagingornncaging operation, ,that is when .henaxts areoperiat nsin themarmer which will .be described'liereinafte'r, the switch 123 is in itsupperposition while thaswiteh 1 .is op n. thu the line vol age is tap pliedin ser e acros the twolamps 14 n .1 and eaeh ampw lhglowdul yto ndieate ha th -parts are in per tionran thatthegy os opetisn ithercag d nor tin-- eage i y. l

It is to be understood that in addition tottherD. C. control and aging ireuit, illustrated in ig- 1.4. other iruit are bro ghtin oh gyrosc pe 'forfurni hing power f the gyros on hee and also. for-p o -ofi purp as descrijbed hereinbefore. The gyroscopic wheel power may he alternating currentlandsuch power is also em-- played .forheatin-g th gyro oope th ug plurality f elongate heaters i147 which are strapped to the clamping bolts 20 (Fig. 1) The current through theheaters147 is controlled by qthe t;hermqstatic element 148 (Fig. .3) whiehisspapedpway fromtheheaters 147 andseparated the ef omby th h ppe ra e p t .lt s imp t nt thatthegyrose n b well sealed g inst en y o del t rious elements' nd. to that en a special sealing meansis p fQvided, as hereinafterdescribed. Set:

tiugoverxthe entire gyroscope is zantopen-ended .case .151.

The bottom plate 23 of the gyroscope frame constitutesa closing.plateelosinggtheqend of the. case '151, as; best isseen 11 in Figs. 2 and 4. The lower plate 23 is provided with a relieved portion 152 which fits within the open bottom end of the case 151. Circumjacent the periphery of the relieved portion 152 is a groove 153 having a resilient sealing O-ring 154 seated therein which is slightly compressed between the bottom of the groove 153 and the inside surface of the case 151 to form a continuous seal around the bottom plate 23, between the plate 23 and the case 151.

In order to keep the case 151 clamped firmly to the bottom plate 23, the outer face of the plate 23 is provided with a groove 156 which is adjacent and paralleling each of the four edges of the plate 23. As best seen in Fig. 2, the groove 156 is slanted outwardly toward the edge 157 of the plate 23. Because of the fact that the corners of the plate 23 and the case 151 are rounded, as shown at 158 (Fig. 1), each of the four grooves 156 opens onto the rounded portion of the corners, as shown in Fig. 1.

Each of the four sides of the case 151 is provided with a similar groove 159 which is adjacent and parallel to the bottom edge 157. The grooves 159 likewise are slanted outwardly toward the edge 157 as shown in Fig. 2, re siding in the grooves 156 and 159 on the respective four sides of the case are four C-shaped channel members 161 having re-entrant flanges 162 engaged in the grooves 156 and 159 to clamp the case 151 firmly down against the bottom plate 23. The channel members 161 are slipped into the respective grooves 156 and 159 from the corners of the case since each of the grooves 156 and 159 communicate with the edge of the plate and case, respectively, as best seen in Fig. 1.

' The channel members 161 are provided with partial transverse slots 163 which give a certain flexibility to the channel members so that each channel member functions as a plurality of individual segments in securing its particular portion of the case 151 to the bottom plate 23.

The overall effect of this manner of mounting is to provide a very firm clamping of the case 151 to the bottom plate 23, particularly at those portions of the casing edge located between any two adjacent corners. It is at this region where the ballooning effect of the rectangular case is most acutely felt, that is to say, there is rarely any clamping problem at the corners where the geometry of the parts insures rigidity but there is a tendency intermediate the corners for the edges of the casing to pull away from the closing plate. By the present clamping method, such tendency is overcome by the relatively firm channel members 161 which exert a downward force to secure case 151 to plate 23 and an inward force to maintain contact between case 151 and seal ring 154. These clamps have the added advantages that they can be installed and removed without special tools and once in place will not loosen or change position under the most severe conditions.

While the channel members 161 have been described as being slipped in from the respective edges of the grooves 156 and 159, it is possible also to construct them with sufficient resilience so that they may be snapped into the grooves directly from the sides instead of being slid in from the ends.

In'any event it is preferred to make the member 161 sufficiently resilient that they will recover from any distortion due to temperature cycling of the secured parts.

It is important in the mounting of the gyroscopic wheel or rotor that there be no shifting whatever between the rotor shaft and the inner gimbal to which it is mounted. In accordance with the present invention means are provided for insuring such a firm mounting.

Referring to Figs. 11, the rotor 32 is shown mounted rotatably to a shaft 171 by means of ball bearings 172. In the present instance the rotor is on the outside of the stator 173 which is afiixed to the shaft 171. This provides the spinning mass with its greatest moment of inertia by placing the mass as far from the rotative axis as possible. This of course is desirablein any gyroscopic equipment.

The shaft 171 is fitted within the inner gimbal 31 and is secured firmly thereto in accordance with the present invention by a securing pin 174. As seen in Fig. 11, the shaft 171 is butted against the inner gimbal 31 at 176. The shaft 171 and the gimbal frame 31 have aligned bores 177 and 178 respectively, of equal diameter. The bore 177 in the shaft 171 is continued by a threaded bore 179 having a slightly smaller diameter than the bore 177 and forming a coaxial inner continuation thereof. The inner end of the pin 174 is reduced slightly in diameter and is threaded to engage the bore 179 in the shaft. The unthreaded smooth portion of the pin 174 is fitted closely within the aligned bores 177 and 178.

The outer surface of the gimbal frame 31 is recessed to receive the head 181 of the pin 174 which thus bears against the gimbal 31 to hold the shaft 171 in close butting engagement with the inside surface of the gimbal 31.

The construction illustrated in Fig. 11 results in the shear forces being resisted by the closely fitting pin 174 at the butting plane 176 while separation forces between the gimbal 31 and the shaft 171 are resisted by the threaded engagement of the inner end of the pin 174 in the threaded bore portion 179 and the head 181 bearing against the gimbal 31. The net result is a precise firm fitting which is capable of resisting normal wear and tear and high shock forces without measurable shift between the rotor and the gimbal.

The shaft 171 is hollow as shown at 182 and communicates with the stator 173 through an outward passage 183. Through this passage wires are led into the stator through the pin 174 which is also hollow as shown at 184. To accommodate the wires during assembly of the gyroscope wheel to the gimbal 31 a lateral groove 186 is formed inside the gimbal 31. These wires reside in the groove 186 during the last phase of the assembly just as the shaft 171 is moved into butting relation within the gimbal 31.

An alternative means of moving the actuating member 58 downward is shown in Fig. 15. In this embodiment the driving ring or nut 73 is eliminated and is replaced by one or more solenoids 191 mounted in the upper frame plate 22. The plungers 192 of the respective solenoids 191 bear against the annular plate 61 and press the actuating member 58 down directly into engagement with the gimbal. In the embodiment shown in Fig. 15 the torque pin 81 is secured directly to the central hub portion 59 of the actuating member. Also eliminated are the solenoid 107; switch 114; arm 84 and spring 87 of the first embodiment. The other parts of the assembly are essentially the same and the operation of this embodiment is essentially the same as the first embodiment.

The wiring of the embodiment shown in Fig. 16 is essentially similar to that shown in Fig. 14 except that the solenoids 191, which are connected in series, replace the solenoid 107 and the transfer switch 114 is eliminated.

Operation The operation of the apparatus described hereinbefore will now be described with particular reference to Figures 7, 8, and 14.

When the switch 137 stands open the gyroscope is uncaged and the green light 143 is lit, which will indicate this condition. Caging is instituted by closing the switch 137-and leaving it closed. Closing of the switch 137 applies voltage simultaneously to the solenoid 107 and the motor 72 through the transfer switch 114. Energizing of the motor 72 causes the central hub portion 59 to be rotated in a given direction by the belt 67. At the same time the solenoid 107 causes the thread engaging toe 86 to engage the bottom portion of the thread 76 (Fig. 8) in the driving ring 73.

Rotation of the hub 59 is imparted to the ring 73 through the key 78 and causes the ring 73 to be screwed downward. As the ring 73 moves downward within the cavity 74, it presses the actuating hub 59 ahead of it through the intermediacy of the spring 87.

Initial downward movement of the annular'plate '61 sel e alt ra n c th We g e-1.16 hrc h the pinf1 1 8 (Fig.) The switch 116 is left open, placing both'of the'ligh'ts 1 43 andin series across the power supply. causes the green light to cease'to glow brightly and 'inst'ead both'the green and red lights will glow 'dully toindicate that the parts are N operating and that the gyroscope is neither fullyfcaged nor fully ung ,v v

The ring-73 continues to move downwardly until the toe-86 snaps into the outer annular groove 92. Simultaneously, the resiliently mounted roller 82 is brought into engagement with the torque ring ortrack'83 on the outer gimbal 29. As the we 86 snaps intothe groove 92 the resulting movement of the lever 84 andsole'noid plungerms causes actuation of the transfer, switch 114 which transfers control'of themotor 72 to the reversing switch The position of the reversing switch 94 will depend upon what has happened'in the meantime to-the sensing probe 49 as'it wasmoved'downby the annular plate 61. If the rollr Sl-has goneinto engagement with the high segment '43 on the disc 41 (see 51a, Fig. 10) then the downward movement of the actuating member 58 will have been halted at such a position that the switch oper ating probe 93 is stillengaged with the cam surface 594. In this event-the motor 72 continues to rotate in the same direction since the reversing switch 94- has notbeenoperated. Continued rotation "of themotor 72 inthe forward direction causes the roller 82 to move around on the torque ring 83 until it snaps into the notch 85 therein, whereupon the outer gimbal 29 is firmly latched or coupled to' the actuating member 58 and 'torque is applied to gimbal 29 through the torque pin 8 1. Thistorque-applied to thegimbal 29 is in the proper direction to cause the inner gimbal 31 to precess so as to rotate the disc 41 Counter-clockwise toithe position shown inFig. 6, thereby bringing the probe 49 into registry with the notch 47.

Reverting'now for a moment,=let it be assumed that the disc 41 was in such position that the lower segment 42 was in registry with the probe 49. In this event, when theroller' 51 engages thesegment 42, the actuating memher 58 will haveheen moved down to such a position that the switch probe 93 hasbeen moved outwardly-by engagement with the camsegrnent or section 59b. In this event, the reversing switch 94 will have been operated to its lower position in Fig. 14 and the motor 72 will have-been reversed,th us the actuating member 58 will nowsbe caused to rotate in the opposite direction as before described the roller -82 will ridden the torque ring 83 until it snaps into the notch 85. Now, however, the torque applied: to the outer gimbal 29 will be in'the opposite direction and the inner gimbal 31 will precess so as to cause the disc 41 to rotateto the position "shown in -Fig. 6.

Thus it will-be'seen that no matterhow the inner gimbal is positioned with respect to the outer gimbal, the sensing means will operate so as to cause the inner gimbal to be moved to its caged position with respect to the outer gimbal so that the probe 49 may moveinto the notch 47 and thus latch the inner gimbal to the outer gimbal in caged position.

'Whenthe roller 51 registers with thenotch 47 the'probe 49 will move downward under the compression force of the spring 87. Said movement will be stopped by engagement of theupper roller96 on the probe 49 with the-track Atthismoment, the-roller 51,'will bein position 51c, shown in Fig. 10, and the probe 93 will be hearing against eitherthe se'gment59c or thesegment 59cc on the hub 59. Thus, the inner gimbal 31 will be fixed or latched in its caged position'tothe outergimbal 29, although this latching will'be rather loose as shown in Fig. 10. Whereas the outer gimbal '29 was virtually immovable as long as the inner gimbal was allowed to precess, oncethe inner gimbal is latched to the outer gimbal, the outer gimbal may be readily rotated; by virtue of the torque appliedto it through the torque pin 81.

1 d e tie of t torque a r t me ut r. mbal 29, will'be dependent upon the reversing switch'94 which will have been actuated to such a position by either he cam-59c or the cam 59cc that a minimum-length of travel is required to bring the roller 96 into registry with the notch 104 in the track :97. 'Hence, the motor '72 w drives thehub 69 and the outer gimbal 29 so as to rotgte the outer gimbal until the roller 96 dropsintqthe notgbh 104 on the track 97.

When this occurs both rollers 96 and 51 will firmlyseat in their respective notches, thus cagingthe outer gimbal 29 to the frameZI and also removing the tolerance in the caging of'theinner gimbal to the outer-gimbal as theroller 51 drops into the tapered portion 48 of the notch 47.

Asfthe roller 96 drops into the notch 104*it moves the leaf spring 127 down thereby operating the caged switch 123 through the pin 124. This moves the caged switch 12-3 to its lower position inFig. 14 de-energizing the motor 72 and shunting the green Signalflight'143. This operation causes the red light -144-to glow brightly indi'cati g that the gyroscope is now in fully caged position. I

Energization of the solenoid 107 continuesto keep the actuating member 58 pressed downward into caged position by virtue of the continued engagement of the-toe in-the groove 92.

Uncaging is effected simplyby opening the switch 137-; Such opening dc-energizes the solenoid 10] allowing spring 109 to retract toe 86 thus allowingthe driving rifig 73 to be driven quickly and linearly upward in the cavity 74 of the hub 59 by spring 87. This operation'isaecorn panied by a rapid lifting of-the entire actuating member 58 by virtue of the spring 8 8. This-rapid and-linearilifting of the actuating member 53 releases'the outer 'gi nbal'29 and simultaneously releases --the inner gimbal '31. The cagingmechanism parts thus quickly resume t-heir'de-energized positions in which both gimbals are free. This releaseiit will be noted occurs rapidly and without any disturbance or kicks which might impart an undesired torque to either gimbal.

In this releasing operation the caged switch is first moved to its upper position in Fig. .14-and immediately thereafterthe uncaged'switch is closed as the annul-arpl-ate 61 engages the pin 118 (Fig. 5-) to close the switchillfi. Thus the'lamp. 144will burndimly in series; with lamp 143 for a moment (during uncaging operation) and the'n g'o darkvas lamp 143 attains full brilliance indicating thatthe gyroscopeis in uncaged position.

.It will'benoted that should -the.uncaging be impeded, the two lamps willburn dimly thus-indicating to the operator amalfunctioningof the apparatus. Thus no phase of the operation is'i'ndicated by adark lamp, whichwould be ambiguouswith a burned-out lamp.

From the above description, it is noted that-the-caging operation is effected by a rotary motionof the driving ring 73. This rotary motion" by virtue of the thread 76-may be made against the opposition of strong springs -88and-87j Without requiring much operating power; at the sameti ne the springs 87 and 88 may be made strongenoughto over come any high accelerations in the air vehicle. At the same time the uncaging operation is achieved bya linear motion of the driving ring 73 thereby'being efiected rapidly and without undesirable disturbance of the gimbals.

It will the further noted that the systemfis a fail'safe system in that if the power should :be cut off, either during the operation of the mechanism or when it is being main tained in caged position, it will immediately-revert to-uncaged position which isthe safer of the two possible attitudes of the system.

Whilethe modification shown in Figs. 15 and '16 is-more suited for low G work than for high G work, it does have the advantage of simplicity in that not as manymovihgparts are required and the transfer switch may be eliminated. Thetransfer switch is required inthefir st ment because of the danger that the reversing switch-94 might be operated before the thread engaging toe 86 has snapped into the upper groove 92, in which event the screw down operation would be reversed prior to completion.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed herein but is to be accorded the full scope of the claims.

What is claimed is:

1. Apparatus for caging a gyroscope having a frame and a plurality of gimbals successively rotatably mounted, one within the other, and a rotor pivotally mounted to the innermost of said gimbals, comprising: means for rotating one of said gimbals with respect to the gimbal within which one said gimbal is mounted, means for latching said one gimbal to said gimbal within which said one gimbal is mounted, means for rotating another gimbal within its mounting, and means for latching said other gimbal to its mounting.

2. Apparatus for caging a gyroscope having a frame, an outer gimbal pivotally mounted to said frame, an inner gimbal pivotally mounted to said outer gimbal, and a rotor pivotally mounted to said inner gimbal, comprising: means for applying a torque to one of said gimbals, thereby to precess the other of said gimbals into caged position, means for latching said gimbals together, means for rotating said one gimbal into caged position, and means for latching said one gimbal in caged position following caging thereof.

3. Apparatus according to claim 2, wherein said one gimbal rotating means comprises means for continuing application of torque to said one gimbal.

4. Apparatus for caging a gyroscope having a frame, an outer gimbal pivotally mounted to said frame, an inner gimbal pivotally mounted to said outer gimbal, and a. rotor pivotally mounted to said inner gimbal, comprising: means for rotating said inner gimbal into caged position with respect to said outer gimbal, means for latching said inner gimbal to said outer gimbal in caged position of said inner gimbal, means for rotating said outer gimbal to caged position in said frame, and means for latching said outer gimbal in caged position, with respect to said frame.

5. Apparatus for caging a gyroscope having a frame, an outer gimbal pivotally mounted to said frame, an inner gimbal pivotally mounted to said outer gimbal, and a rotor pivotally mounted to said inner gimbal, comprising: means for applying a torque to said outer gimbal thereby to precess said inner gimbal into caged position, and means for rotating said outer gimbal into caged position following caging of said inner gimbal.

6. Apparatus for caging a gyroscope having a frame, an outer gimbal pivotally mounted to said frame, an inner gimbal pivotally mounted to said outer gimbal, and a rotor pivotally mounted to said inner gimbal, comprising means for applying a torque to said outer gimbal thereby to precess said inner gimbal into caged position, means for latching said inner gimbal to said outer gimbal in the caged position of said inner gimbal, means for rotating said outer gimbal into caged position following caging of said inner gimbal, and means for latching said outer gimbal to said frame in caged position of said outer gimbal.

7. Apparatus for caging a gyroscope having a frame, an outer gimbal pivotally mounted to said frame, an inner gimbal pivotally mounted to said outer gimbal, and a rotor pivotally mounted to said inner gimbal, comprising: means for effecting a torque, means for coupling said torque means to said outer gimbal, thereby to precess said inner gimbal into caged position, means for latching said inner gimbal to said outer gimbal in caged position of said inner gimbal, means for efiecting continued application of torque to said outer gimbal 16 from said torque means thereby to rotate said outer gimbal into caged position following caging of said inner gimbal, and means for latching said outer gimbal to said frame in caged position of said outer gimbal.

8. Apparatus for caging a gyroscope having a frame, an outer gimbal pivoted to said frame, an inner gimbal pivoted to said outer gimbal and a rotor pivoted to said inner gimbal, comprising: rotative drive means mounted on said frame, coaxially with said outer gimbal, means for latching said drive means to said outer gimbal thereby to effect application of a torque to said outer gimbal by said drive means, and to thus precess said inner gimbal into caged position, means for latching said inner gimbal to said outer gimbal in the caged position of said inner gimbal after said inner gimbal has processed into caged position, means for latching said outer gimbal to said frame in caged position after said outer gimbal has been rotated into caged position by said drive means, and means for de-energizing said drive means in response to latching of said outer gimbal in its caged position.

9. Apparatus for caging a gyroscope having a frame, an outer gimbal pivoted to said frame, an inner gimbal pivoted to said outer gimbal, and a rotor pivoted to said inner gimbal, comprising: rotative drive means mounted on said frame coaxially with said outer gimbal, means for latching said drive means to said outer gimbal thereby to effect application of a torque to said outer gimbal by said drive means and to thus precess said inner gimbal into caged position, inner gimbal sensing means for sensing the position of said inner gimbal with respect to said outer gimbal, means for controlling the direction of torque applied to said outer gimbal by said drive means in response to said inner gimbal sensing means, means for latching said inner gimbal to said outer gimbal in the caged position of said inner gimbal after said inner gimbal has precessed to said caged position, outer gimbal sensing means for sensing the position of said outer gimbal in said frame, means for controlling the direction of torque applied to said outer gimbal by said drive means in response to said outer gimbal sensing means, means for latching said outer gimbal to said frame in caged position after said outer gimbal has been rotated into caged position by said drive means, and means for de-energizing said drive means in response to latching of said outer gimbal with respect to said frame.

10. Apparatus in accordance with claim 9 wherein said inner gimbal sensing means comprises: a disc secured coaxially to said inner gimbal and having at least two peripheral segments of different radius, and a notch formed in the periphery of said disc between said two segments, a latching and sensing member movably mounted in said outer gimbal and effective to be engaged with the periphery of said disc, said rotative drive means comprising a ring-like actuating member mounted for axial and rotative movement, said actuating member comprising a central portion and an annular plate rotatably secured to said central portion and having a peripheral groove therearound, said sensing member being engaged in said plate groove to be actuated back and forth by axial movement of said actuating member, said actuating member having on the outer surface of said central portion a plurality of annular cam surfaces, means for moving said actuating member axially, reversing switch means having an operating member in engagement with said cam surfaces to be actuated in accordance with the axial position of said actuating member, an electric drive motor coupled to said actuating member to rotate the same, circuit means interconnecting said reversing switch means with said motor to control the direction of rotation of said motor in accordance with the axial position of said actuating member, said outer gimbal sensing means being comprised of a portion of said annular cam surfaces on said actuating member, one arcuate segment of said portion being of a given radius and another arcuate segment of said portion being of a different radius,

thereby to detennine the attitude of said reversing switch in accordance with the angular position of said actuating member, said outer gimbal latching means comprising circular track means secured to said frame and having a notch therein, said inner gimbal sensing member having a portion riding on said track means and engageable in said notch when said outer gimbal is in its caged position, said drive means de-energizing means comprising caging switch means connected in the energizing circuit for said drive motor, and an operating member for said caging switch means operable in response to engagement of said inner gimbal sensing member in said rail notch.

11. Apparatus in accordance with claim wherein said actuating member moving means comprises a driving ring disposed within said actuating member central portion and keyed thereto, said drivingring being threaded internally, a thread engaging member movably mounted on said frame and selectively engageable with said dn'ving ring threads to effect axial movement of said ring upon rotation thereof, resilient means axially interconnecting said driving ring and said actuating member, and means biasing said driving ring with respect to said frame away from said outer gimbal.

12. Apparatus according to claim 10 wherein said ac tuating member moving means comprises solenoid means having operating means efiective to move said actuating member axially toward said outer gimbal.

13. Method of caging a gyroscope including a frame, an outer gimbal pivoted to said frame, an inner gimbal pivoted to said outer gimbal, and a rotor pivoted to said inner gimbal, comprising: precessing said inner gimbal by applying a torque to said outer gimbal until said inner gimbal has arrived at caged position, latching said inner gimbal to said outer gimbal in caged position, rotating said outer gimbal in said frame until said outer gimbal has reached caged position, and latching said outer gimbal to said frame in its caged position.

14. Method of caging a gyroscope including a frame,

an outer gimbal pivoted to said frame, an inner gimbal pivoted to said outer gimbal and a rotor pivoted to said inner gimbal, comprising: sensing the position of said inner gimbal with respect to said outer gimbal, precessing said inner gimbal in a predetermined direction in accordwce with said sensing by applying a torque to said outer gimbal until said inner gimbal has arrived at caged position, latching said inner gimbal to said outer gimbal in caged position of said inner gimbal, sensing the position of said outer gimbal with respect to said frame, rotating said outer gimbal in said frame in accordance with the sensed position thereof until said outer gimbal has reached caged position, and latching said outer gimbal to said frame in caged position of said outer gimbal.

15. Method of caging a gyroscope including a frame, an outer gimbal pivoted to said frame, an inner gimbal pivoted to said outer gimbal, and a rotor pivoted to said inner gimbal, comprising: rotating said inner gimbal to caged position with respect to said outer gimbal, latching said inner gimbal to said outer gimbal in caged position of said inner gimbal, rotating said outer gimbal to caged position with respect to said frame, and latching said outer gimbal to said frame in caged position of said outer gimbal.

References Cited in the file of this patent UNITED STATES PATENTS 2,124,817 Fieux July 26, 1938 2,182,201 Harris Dec. 5, 1939 2,383,663 MacCallum et al Aug. 28, 1945 2,384,310 Judd Sept. 4, 1945 2,410,002 Bach Oct. 29, 1946 2,436,407 Stephens Feb. 24, 1948 2,441,307 A Alkan May 11, 1948 2,469,782 Phair May 10, 1949 2,513,383 Van Armbruster July 4, 1950 2,591,741 Stone Apr. 8, 1952 2,645,129 Brown July 14, 1953 

